The invention relates to an apparatus for repeatedly rinsing body cavities with sterile fluids by periodic filling and emptying, with measurement of the additional quantity of fluid removed from the cavity. Some examples of its application are peritoneal dialysis and rinsing of the bladder. The description which follows relates particularly to use in peritoneal dialysis.
The normal process of peritoneal dialysis consists of introducing a certain quantity of a rinsing fluid through a catheter inserted in the body cavity of the patient, then emptying it again, possibly after waiting for a certain time. The process is repeated several times in the course of a treatment. Due to osmotic effects the quantity of fluid flowing out is generally somewhat larger than the quantity introduced. Measurement of the additional quantity of fluid flowing out is of considerable interest in appraising the treatment.
In known peritoneal dialysis machines some do not attempt to draw up a balance, i.e. do not ascertain the additional quantity of fluid removed. Some machines draw up a balance by measuring the quantity of fluid supplied and the quantity removed in two identical measuring vessels with level electrodes, and by drawing off the excess fluid present separately and collecting it in a third measuring vessel when the discharge vessel is full. However, trouble is liable to occur in measuring the level with the fitted level electrodes, e.g. because of possible foam formation in the measuring chambers, and the fact that the volume introduced is fixed imposes a certain limitation. Another known machine operates with variable volumetric dosing or measurement of the quantities flowing in and out, thus avoiding one disadvantage of the previous machine, although this method has also not proved itself in practice because of the high cost and the likelihood of trouble.
DT-AS 2 101 168 describes a peritoneal dialysis machine in which the fluids flowing in and out are measured in flexible bags located in an enclosed, rigid, water-filled container, so that the sum of the quantities of fluid in both bags is kept constant and the inflow and outflow can be directly compared. A disadvantage of this machine is the manipulation necessary to insert the bags, in view of the requirement that the surrounding container must be completely sealed and completely full of water. This is not very practicable in view of the need to change the bags at every use, since they are components of a once usable tube system.
The invention aims to provide a peritoneal dialysis machine which will enable the additional quantity of fluid flowing out to be ascertained exactly, with simple and easily operated technical means and without any precision measuring instruments.